For such applications as communication equipment, and electronic instruments, input signals are usually presented as analog waveforms. However, in systems based on pulse circuits, such as pulse analyzers, pulse communication systems or pulse-code modulation TV systems, input analog signals must be converted into pulse signals to allow complex signal analysis and processing to be carried out. To prevent weak signal components from being lost in background, and strong signal components from overloading the signal processing system, an analog signal may be compressed before its conversion into a pulse signal.
Various compression schemes have been developed to compress an analog signal before its conversion. For example, U.S. Pat. No. 5,023,490 to Gittinger of Jun. 11, 1991 discloses a circuit for performing a monotonic compression function over an AC signal before supplying the AC signal to a high-frequency analog-to-digital converter. The compression circuit comprises multiple limiter stages, each of which contains a wide-band cascode amplifier and current-mirror devices. Thus, the prior art arrangement requires separate circuits for carrying out analog signal compression and conversion procedures.
To reduce the number of components required to perform analog signal compression and conversion, it would be desirable to provide a single circuit that combines the conversion of an analog signal into a pulse signal with the compression of the analog signal.
Also, to increase the operating speed of a signal processing system, it would be desirable to provide a circuit that carries out the conversion of an analog signal into a pulse signal and the compression of the analog signal in a single step.